I work on Cloudflare Tunnel, which lets customers quickly connect their private services and networks through the Cloudflare network without having to expose their public IPs or ports through their firewall. Tunnel is managed for users by cloudflared, a tool that runs on the same network as the private services. It proxies traffic for these services via Cloudflare, and users can then access these services securely through the Cloudflare network.
Recently, I was trying to get Cloudflare Tunnel to connect to the Cloudflare network using a UDP protocol, QUIC. While doing this, I ran into an interesting connectivity problem unique to UDP. In this post I will talk about how I went about debugging this connectivity issue beyond the land of firewalls, and how some interesting differences between UDP and TCP came into play when sending network packets.
cloudflared works by opening several connections to different servers on the Cloudflare edge. Currently, these are long-lived TCP-based connections proxied over HTTP/2 frames. When Cloudflare receives a request to a hostname, it is proxied through these connections to the local service behind cloudflared.
While our HTTP/2 protocol mode works great, we’d like to improve a Continue reading
I was happily munching popcorn while watching the latest season of Lack of DHCPv6 on Android soap opera on v6ops mailing list when one of the lead actors trying to justify the current state of affairs with a technical argument quoted an RFC to prove his rightful indignation with DHCPv6 and the decision not to implement it in Android:
[…not having multiple IPv6 addresses per interface…] is also harmful for a variety of reasons, and for general purpose devices, it’s not recommended by the IETF. That’s exactly what RFC 7934 is about - explaining why it’s harmful.
I have been playing around with Python lately with the goal of building basic skills in it. I have found that to make good progress what works best for me is:
The project I decided on was to get the IP addresses that AWS uses for their services, build an access-list based on these prefixes, and then configure a Cisco ASA with that access-list. The final result looks like this:
In a series of blog posts, I will cover how I built this script. Keep in mind that my focus was to get a script that works and then improve on it. I have some plans for getting an experienced Python coder to go through the code with me and to work on improvements. Stay tuned for that!
As with any coding project, you need to come up with some general guidelines on how to get data and what is good enough. These are some of the considerations I had:
Over the last few years, Zero Trust, a term coined by Forrester, has picked up a lot of steam. Zero Trust, at its core, is a network architecture and security framework focusing on not having a distinction between external and internal access environments, and never trusting users/roles.
In the Zero Trust model, the network only delivers applications and data to authenticated and authorised users and devices, and gives organisations visibility into what is being accessed and to apply controls based on behavioural analysis. It gained popularity as the media reported on several high profile breaches caused by misuse, abuse or exploitation of VPN systems, breaches into end-users’ devices with access to other systems within the network, or breaches through third parties — either by exploiting access or compromising software repositories in order to deploy malicious code. This would later be used to provide further access into internal systems, or to deploy malware and potentially ransomware into environments well within the network perimeter.
When we first started talking to CISOs about Zero Trust, it felt like it was just a buzzword, and CISOs were bombarded with messaging from different cybersecurity vendors offering them Zero Trust solutions. Recently, another term, SASE (Secure Continue reading
Cloudflare Workers is our serverless platform that runs your code in 250+ cities worldwide.
On the Workers team, we have a policy:
A change to the Workers Runtime must never break an application that is live in production.
It seems obvious enough, but this policy has deep consequences. What if our API has a bug, and some deployed Workers accidentally depend on that bug? Then, seemingly, we can't fix the bug! That sounds… bad?
This post will dig deeper into our policy, explaining why Workers is different from traditional server stacks in this respect, and how we're now making backwards-incompatible changes possible by introducing "compatibility dates".
TL;DR: Developers may now opt into backwards-incompatible fixes by setting a compatibility date.
Workers is a serverless platform, which means we maintain the server stack for you. You do not have to manage the runtime version, you only manage your own code. This means that when we update the Workers Runtime, we update it for everyone. We do this at least once a week, sometimes more.
This means that if a runtime upgrade breaks someone's application, it's really bad. The developer didn't make any change, so won't be watching for Continue reading
The whole High Availability Switching series started with a question along the lines of “does it make sense to run BFD together with Graceful Restart”. After Non-Stop Forwarding 101, Graceful Restart 101, and Graceful Restart and Convergence Speed we finally have enough information to answer that question.
TL&DR: Most probably not.
A more nuanced answer depends (as always) on a gazillion implementation details.
In the midst of the hottest summer on record, Cloudflare held its first ever Impact Week. We announced a variety of products and initiatives that aim to make the Internet and our planet a better place, with a focus on environmental, social, and governance projects. Today, we’re excited to share an update on Crawler Hints, an initiative announced during Impact Week. Crawler Hints is a service that improves the operating efficiency of the approximately 45% of Internet traffic that comes from web crawlers and bots.
Crawler Hints achieves this efficiency improvement by ensuring that crawlers get information about what they’ve crawled previously and if it makes sense to crawl a website again.
Today we are excited to announce two updates for Crawler Hints: